We purchased a cast iron skillet when we first got here a few weeks ago because we needed something to cook with until our kitchen stuff arrives. I chose cast iron because I've been wanting one for a while and didn't want to purchase something we already had.
It has taught me a lot about relationships.
When dealing with cast iron, you have to treat it very well in order to assure it's long life and cooking quality. Washing must be done almost immediately. You cannot just let it sit in the sink or it will rust. You cannot use harsh soaps (or really any soap at all), nor can you scrub it too much or the seasoning gets ruined. You can't just shove it in the dishwasher and hope it gets the job done. In essence, you really have to care for it or you'll ruin it.
Relationships work the same way. You can't just let problems sit, you can't treat them harshly. You can't hope that by haphazardly "dealing" with an issue that comes up that the issue will be taken care of. Lazily attending to your relationships can cause damage and wear it out quickly. Relationships take time, dedication and great care.
All this from a skillet.